Air seeders are well known for seeding agricultural crops. Air seeders typically comprise a frame with furrow openers mounted thereon that are configured to create furrows in a field surface. For best results it is desirable to deposit seed, and other agricultural products such as fertilizer, in the bottom of the furrow. Air seeders include one or more tanks containing agricultural products, a conduit network connected between the tanks and the furrow openers, and a fan to create an air stream flowing from the tanks to the furrow openers. The delivery conduits are connected at their output ends to direct the products into the bottom of the furrows. The air flow must be sufficient to maintain the agricultural products in the air stream. When the air stream is too slow, the product drops out of the air flow and plugs the conduit.
As farmers farm larger tracts of land, air seeders have become wider, and the conduit network longer. Longer conduits require a higher velocity air stream in order to ensure the products are maintained in the air stream. Higher velocities however have detrimental effects on seed placement at the bottom of the furrow. Seeds traveling at high speed out of the output end of a delivery conduit often hit the bottom of the furrow and then bounce up, landing in the looser soil above the bottom of the furrow, or even bouncing completely out of the furrow.
Furrow openers are often further configured to create two or more separate furrows, and to deposit one agricultural product, such as fertilizer into one furrow, and a different product, such as seed, into another furrow. When velocity is excessive the products can often bounce or blow into the wrong location and result in reduced effectiveness.
To address this problem various devices have been developed to slow down the agricultural products before they exit the output end of the delivery conduit, so that the material will drop into the bottom of the furrow and stay there. Air release chambers, also commonly referred to as seed brakes, are available. These seed brakes comprise generally a chamber placed in series in a conduit, typically in proximity to the outlet end thereof, such that the air stream enters the chamber, and air is released through a screen in the chamber walls that prevents the seed from blowing out with the air. Baffles may also be provided in the chamber to further slow the seed as it strikes the baffles. Such a seed brake is available from Dutch Industries Ltd. of Pilot Butte, Saskatchewan, Canada. U.S. Pat. No. 5,522,328 to Long also discloses a similar seed brake with an air release and baffles.
A cyclone type air release chamber is also available where the air stream carrying the agricultural products enter a cyclone which separates the products from the air stream and allows the product to fall down into the trench. Such a device is available from Invenco Pty Ltd. of Sydney, Australia.
In such devices the seed hits the hard surfaces of baffles which can damage the seed, especially sensitive seeds such as peas and bean. The devices also often leave the seed moving at an excessive rate.